Immobilization of Pb, Cd and Cr by synthetic NaP1 zeolites from coal bottom ash treated by density separation (第6回資源リサイクル・材料科学に関する日韓国際シンポジウム特集号)

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This paper describes a study of the immobilization of Pb2+, Cd2+ and Cr3+ by synthetic zeolites formed as a result of the hydrothermal treatment of coal bottom ash (CBA) in alkali-solution after physical separation in below 1.8 specific gravity. The majority zeolite formed at 120°C was a NaP1 species (Na6Al6Si10O32·12H2O) showing gismondine-type appeared in large clusters of tetragonal prisms. The CBA was separated into four kinds depending on specific gravity(S); below 1.8S, 1.8–2.2S, 2.2–2.5S and above 2.5S. NaP1 zeolite could be more synthesized by using the CBA in below 1.8S. The adsorption behavior of hydrothermally treated CBA in 2M NaOH at 120°C after density separation in below 1.8S was studied with respect to Pb2+, Cd2+ and Cr3+ in order to consider its application to purify wastewater. The Langmuir model was found to describe the adsorption process well, offering a maximum adsorption capacity of 15.4 mg/g Pb, 12.7 mg/g Cd and 5.4 mg/g Cr.
2009-09-10